A device is known from DE 33 02 379 C2. A retainer is provided on a carrier arm that is displaceably mounted, via a rolling contact bearing, onto an agricultural implement. A coupling sleeve is rotatably supported, by the rolling contact bearing, which is non-rotatably connected to a joint yoke of a universal joint of a universal joint shaft. The coupling sleeve can be non-rotatably connected to a coupling hub by longitudinal teeth. The coupling sleeve is again non-rotatably connected to a power take-off shaft of a tractor. The coupling sleeve has an inner circumferential groove. In the coupled position, locking balls are pushed by a releasing flange radially outwards into the inner circumferential groove. This prevents an unintended detachment of the coupling sleeve. Only by displacing the releasing flange can the locking balls move inward, so that the coupling sleeve can be pulled off the coupling hub.
The tractor is reversed towards the implement until the coupling sleeve is connected to the coupling hub coupling the two. Beforehand, the carrier arm has to be exactly aligned to the height and the lateral position of the coupling hub. Thus, a direct coupling is enabled between the coupling sleeve and the coupling hub.
EP 1 637 024 A1 shows a coupling frame that is attached on a three point linkage of a tractor. Coupling hooks for a three-point coupling of an implement are provided on the coupling frame. Furthermore, a coupling element is rotatably and axially displaceably supported on the coupling frame. The coupling element is connected to a universal joint shaft. Also, the coupling is connected to the power take-off shaft of the tractor. As soon as the implement is coupled to the coupling frame, the coupling element on the coupling frame is arranged in a centered position relative to the coupling element on the implement. The position relative to the three-point coupling of both coupling elements is identical. The coupling element on the coupling frame is then manually displaced by a moving lever axially in the direction toward the implement. The coupling elements, in the form of a jaw clutch coupling, are brought into engagement.
EP 1 563 723 A1 shows a device for coupling a universal joint shaft to a power take-off shaft of a tractor. A yoke-like coupling element is provided on the tractor and is axially displaceable parallel to the rotational axis of the power take-off shaft of the tractor. In an extended position, a coupling element of the universal joint shaft can be inserted radially into the rotational axis between two arms of the yoke-like coupling element. The coupling element of the universal joint shaft has a groove and is formed rotationally symmetrically to the rotational axis. The yoke-like coupling element engages the coupling element. The yoke-like coupling element can be pulled axially towards the power take-off shaft. The coupling element of the universal joint shaft is also axially displaced. Due to the pulling, the coupling element of the universal joint shaft is pulled onto the power take-off shaft. The longitudinal teeth provide a non-rotatable connection between the power take-off shaft and the coupling element of the universal joint shaft.